Add Tj Retry-After Code to wp-maintenance-mode.php Please Consider Because helps with Google

Added block of code to help establish Retry-After header content based on the date picker data chosen by user in Admin panel.

Google likes this. Consider this...

http://googlewebmastercentral.blogspot.com/2011/01/how-to-deal-with-planned-site-downtime.html

Thanks,
-TJ